Objective To perform a comparative bioinformatics analysis of H5 hemagglutinin of different strains of H5N1 avian influenza virus for elucidating its molecular characteristics.Meth-ods The amino acid and nucleotide sequences of H5 hemagglutinin of 15 different strains of H5N1 avian influenza A virus were retrieved from GeneBank.SignalP4.1 software was used to predict the signal peptide.Softwares Clustal X and Bioedit were used to align different amino acid and nucleotide sequences and to calculate their homology.AntheProt5.0 software was used to predict the secondary structures.Results The ORF length of H5 hemagglutinin of 15 strains of H5N1 influenza A virus was 1707 bp(8 strains)/1704 bp(7 strains),which encoded a peptide of 568 or 567 amino acids.Nucleotide and amino acid identity of H5 Hemagglutinin of different strains of H5N1 influenza A Virus ranged from 85.6%-99.5% and 86.7%-99.2%,respectively. Theα-helix(29%-35%),β-sheet(22%-25%)and coil(22%-25%)were found in the secondary structures of H5 hemagglutinin.The amino acid sequence locating at aa1-aa16 was the potential signal peptide.The cleavage sequence of A1 and A2 subunits was RERRRKKR↓GLF that loca-ted between aa323 and aa333 with cleavage site between R330 and G331.A1 subunit harbored four hypervariable regions:aa115-aa140(52.0%),aa151-aa170(57.9%),aa183-aa200(64.7%) and aa263-aa280(47.4%).The ten cysteine sites involved in the formation of disulfide bond re-mained stable.The E186,K212,S217-K218,G221-Q222-S223-G224 and other receptor-binding sites were conservative.T cell and B cell epitopes aa141-155、aa206-223 and aa302-316 were also conservative.Conclusion The sequences of receptor-binding domain and T cell and B cell epitopes are conservative and stable in H5 hemagglutinin of H5N1 avian influenza A virus.The cleavage sequence of A1 and A2 subunits carries 6 consecutive basic amino acids(R/K)associated with high pathogenicity.%目的 通过比较不同来源的 H5N1甲型流感病毒 H5血凝素蛋白生物信息学,分析 H5N1甲型流感病毒H5血凝素蛋白的分子特征.方法 从Gene Bank基因数据库中获取15株H5N1甲型流感病毒H5血凝素蛋白的核苷酸和氨基酸序列,采用在线软件SignalP4.1预测信号肽,运用Clustal X,Bioedit等国际通用软件进行氨基酸和核苷酸的序列比对,计算核苷酸及氨基酸的同源性.在线软件 Antheprot分析二级结构.结果 15株 H5血凝素蛋白编码框架长约1707 bp(8株)/1704 bp(7株),编码含568个/567个氨基酸组成的多肽.H5血凝素氨基酸同源性为86.7%~99.2%,核苷酸同源性为85.6%~99.5%,H5血凝素蛋白富含潜在α螺旋(29%~35%)、β折叠(22%~25%)和卷曲结构(22%~25%)等二级结构.H5血凝素蛋白 aa1-aa16区域为潜在信号肽,血凝素蛋白 A1和 A2裂解序列为 aa323-aa333之间的 RERRRKKR↓GLF 序列,切割位点位于 R330和 G331之间;H5血凝素蛋白 A1亚单位存在4个高变区,分别是aa115-aa140(52.0%)、aa151-aa170(57.9%)、aa183-aa200(64.7%)和aa263-aa280(47.4%).但参与二硫键形成的10个半胱氨酸位点均未发生变异;构成受体结合域的 E186、K212、S217-K218、G221-Q222-S223-G224等位点较保守;构成T细胞和B细胞表位 aa141-155、aa206-223和 aa302-316等区域较保守.结论 H5N1甲型流感病毒 H5血凝素蛋白的受体结合域和免疫表位等重要功能结构域的序列比较保守稳定,在 A1和 A2裂解位点含高致病禽流感病毒分子特征相关的连续6个碱性氨基酸(R/K)序列.
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